Method and control assembly for operating at least two lifting devices, in particular cranes, in parallel

Abstract

A method and control assembly are provided for operating at least two lifting devices, such as cranes, in group and normal operation modes. Each lifting device has a control system connected to a control switch, and the lifting devices are controlled through a common bus. In group operation, the lifting devices are jointly controlled through the bus by one switch. To operate at least two lifting devices in parallel, one of the switches is active in the group operation and the remaining switch or switches are passive. To prepare for group operation, normal operation is deselected by all but one of the control switches to release a remaining switch for log-in to the active state for group operation. To prepare for normal operation, group operation is deselected and normal operation is selected at the active switch before the other switch or switches are released for logging into normal operation.

The invention claimed is:  
     
       1. A method for operating at least two lifting devices, in particular cranes, in group operation and in normal operation modes, said method comprising:
 controlling the at least two lifting devices through a common bus, wherein each of the lifting devices comprises a respective electric lifting gear motor with a respective control system that is connected to a respective control switch, wherein the control switches are selectable between normal operation and group operation; 
 preparing for changing from normal operation to group operation by deselecting normal operation at all but a first of the control switches that are in a normal operation, whereby only the first control switch remains in normal operation; 
 logging on to group operation with the first control switch, thereby changing the first control switch to an active state for group operation, wherein the other control switch or switches that are deselected from normal operation are in a passive state in group operation; 
 jointly controlling the at least two lifting devices though the common bus with the first control switch; 
 preparing for changing from group operation to normal operation by deselecting group operation and selecting normal operation at the first control switch; and 
 logging on to normal operation with the other control switch or switches. 
 
     
     
       2. The method of  claim 1 , wherein the first control switch in the active state for group operation is operable in three operational modes comprising (i) tandem operation in which the at least two lifting devices are controlled in parallel by the first control switch in the active state, (ii) first single operation in which only a first one of the lifting devices is controlled by the first control switch in the active state, and (iii) second single operation in which only a second one of the lifting devices is controlled by the first control switch in the active state. 
     
     
       3. The method of  claim 2 , further comprising monitoring the logging-on and a logging-off of the first and second control switches with the first and second control systems. 
     
     
       4. The method of  claim 3 , wherein the first and second lifting devices further comprise respective crane travel motors and respective trolley travel motors, and the control assembly further comprises first and second crane control systems that are connected to the common bus, said method further comprising:
 allocating the first and second control systems to the respective lifting gear motors and to the respective trolley travel motors; and 
 allocating the first and second crane control systems to the crane travel motors and the crane control systems. 
 
     
     
       5. The method of  claim 2 , wherein the first and second lifting devices further comprise respective crane travel motors and respective trolley travel motors, and the control assembly further comprises first and second crane control systems that are connected to the common bus, said method further comprising:
 allocating the first and second control systems to the respective lifting gear motors and to the respective trolley travel motors; and 
 allocating the first and second crane control systems to the crane travel motors and the crane control systems. 
 
     
     
       6. The method of  claim 1 , further comprising monitoring the logging-on and a logging-off of the first and second control switches with the first and second control systems. 
     
     
       7. The method of  claim 3 , wherein the first and second lifting devices further comprise respective crane travel motors and respective trolley travel motors, and the control assembly further comprises first and second crane control systems that are connected to the common bus, said method further comprising:
 allocating the first and second control systems to the respective lifting gear motors and to the respective trolley travel motors; and 
 allocating the first and second crane control systems to the crane travel motors and the crane control systems. 
 
     
     
       8. The method of  claim 1 , wherein the first and second lifting devices further comprise respective crane travel motors and respective trolley travel motors, and the control assembly further comprises first and second crane control systems that are connected to the common bus, said method further comprising:
 allocating the first and second control systems to the respective lifting gear motors and to the respective trolley travel motors; and 
 allocating the first and second crane control systems to the crane travel motors and the crane control systems. 
 
     
     
       9. A control assembly for operating at least two lifting devices, in particular cranes, in group operation and in normal operation modes, wherein each lifting device has an electric lifting gear motor with an associated control system that allows the at least two lifting devices to be jointly controlled through a common bus, said control assembly comprising:
 a first control switch operatively connected to a first of the control systems associated with a first of the at least two lifting devices, wherein the first control switch is selectable between normal operation and group operation; 
 a second control switch operatively connected to a second of the control systems associated with a second of the at least two lifting devices, wherein the second control switch is selectable between normal operation and group operation; 
 wherein when normal operation is deselected at the second control switch so that only the first control switch remains in normal operation, the first control switch is operable for logging on to group operation, whereby the control systems are configured for group operation in which the first and second lifting devices are jointly controllable by the first control switch via the common bus; 
 wherein when the control systems are configured for group operation so that the first and second lifting devices are jointly controllable by the first control switch, the first control switch is in an active state and the second control switch is in a passive state; and 
 wherein when group operation is deselected at the first control switch and normal operation is selected at the first control switch, the second control switch is operable for logging on to normal operation, whereby the control systems are configured for normal operation in which the first and second lifting devices are independently and respectively controllable by the first control switch and the second control switch. 
 
     
     
       10. The control assembly of  claim 9 , wherein the first control switch in the active state in group operation is operable in three operational modes comprising (i) tandem operation in which the first control switch in the active state controls the at least two lifting devices in parallel, (ii) first single operation in which the first control switch in the active state controls only the first lifting device, and (iii) second single operation in which the first control switch in the active state controls only the second lifting device. 
     
     
       11. The control assembly of  claim 10 , wherein the common bus comprises a respective conducted bus portion associated with each of the at least two lifting devices, and a wireless bus in communication between the at least two lifting devices. 
     
     
       12. The control assembly of  claim 11 , wherein the first and second control systems are operable to monitor the logging-on and a logging-off of the first and second control switches. 
     
     
       13. The control assembly of  claim 12 , wherein the first and second lifting devices further comprise respective crane travel motors and respective trolley travel motors, wherein the first and second control systems are allocated to the respective lifting gear motors and to the respective trolley travel motors, and wherein the control assembly further comprises first and second crane control systems that are connected to the common bus and are allocated to the crane travel motors and the crane control systems. 
     
     
       14. The control assembly of  claim 10 , wherein the first and second control systems are operable to monitor the logging-on and a logging-off of the first and second control switches. 
     
     
       15. The control assembly of  claim 10 , wherein the first and second lifting devices further comprise respective crane travel motors and respective trolley travel motors, wherein the first and second control systems are allocated to the respective lifting gear motors and to the respective trolley travel motors, and wherein the control assembly further comprises first and second crane control systems that are connected to the common bus and are allocated to the crane travel motors and the crane control systems. 
     
     
       16. The control assembly of  claim 9 , wherein the common bus comprises a respective conducted bus portion associated with each of the at least two lifting devices, and a wireless bus in communication between the at least two lifting devices. 
     
     
       17. The control assembly of  claim 16 , wherein the first and second control systems are operable to monitor the logging-on and a logging-off of the first and second control switches. 
     
     
       18. The control assembly of  claim 9 , wherein the control systems and the control switches are connected to the common bus. 
     
     
       19. The control assembly of  claim 9 , wherein the first and second control systems are operable to monitor the logging-on and a logging-off of the first and second control switches. 
     
     
       20. The control assembly of  claim 9 , wherein the first and second lifting devices further comprise respective crane travel motors and respective trolley travel motors, wherein the first and second control systems are allocated to the respective lifting gear motors and to the respective trolley travel motors, and wherein the control assembly further comprises first and second crane control systems that are connected to the common bus and are allocated to the crane travel motors and the crane control systems.